We are developing transition edge sensor (TES) microcalorimeter arrays for future Japanese astronomy missions. Although 6.6 eV energy resolution for 5.9 keV and 74 μs decay time are achieved, our energy resolution was limited by the excess noise of unknown origin. The dominant noise showed 1/R dependence and it only appeared when the current through the TES, I, is larger than 10 μA. This is explained if we assume a constant voltage noise source with a level of ∼2(4kTCRn)1/2. We also investigated the influence of I on the TES performance and found the TES sensitivity α is reduced when the ratio of current to the critical current I/IC is large. It can explain the reduction of α observed when operated without a magnetic shield. We also found a strong correlation between IC and α or the baseline width. Thus, we conclude that IC is an essential parameter for the TES performance.
|ジャーナル||Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment|
|出版ステータス||出版済み - 3 11 2004|
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